MAASTRICHT, THE NETHERLANDS–After mentioning the excavations in the Maastricht Formation limestones (latest Cretaceous) in the last post, I expected to be moving on the next day to a quarry. I hadn’t read the guidebook closely enough: we were planning to spend the afternoon in them! Thinking of my last geology-in-tunnels experience in Russia, I was a bit apprehensive. This time, though, the tunnels were relatively dry, much wider and taller (no sliding on your belly for 30 feet!), and far more stable.
The tunnels under Maastricht are incredibly complex, the product of hundreds of years of mining. The walls often show charcoal drawings of amazing complexity, some dating back to the 17th Century. On our particular route was a Roman Catholic chapel fashioned out of a few galleries by painting the rock walls, adding statuary and carving a pulpit. It was a refuge for the Catholic community when revolutionary French soldiers took over the town at the end of the 18th Century.
Our tour had a geological purpose. We saw, in three dimensions, what may be the most complete Cretaceous-Paleogene boundary known. I learned a great deal about the end-Cretaceous extinction event, especially that the story is getting more complex and surprising. More on that in a later post.